The overall objective of this application is to understand how autophagy and inflammation, particularly in the context of lung endothelium, are activated in association to control acute lung injury (ALI). The rationale for the study is based on our novel finding that phospholipase C epsilon (PLC?), a bifunctional PLC isoform with primary sites of expression in the lung and heart, acts as a critical regulator of autophagy and inflammation in the lung and that inhibiting autophagy ameliorates LPS-induced lung vascular leak. Our published data and ongoing work show that mechanistic (formerly mammalian) target of rapamycin (MTOR), a known inhibitor of autophagy, also functions as endogenous modulator of EC inflammation. Furthermore, we have identified an important role of PLC? in causing down-regulation of MTOR levels in the lungs of mice challenged with LPS. Based on these findings, we propose to test the hypothesis that activation of endothelial PLC? down-regulates MTOR levels/signaling to induce autophagy in association with inflammation to cause ALI. Aim 1 will (i) ascertain the role of PLC? in mediating EC autophagy and inflammation, (ii) assess the contribution of autophagy to EC inflammation and apoptosis, (iii) determine the in vivo role of endothelial PLC? in causing lung inflammation and injury, and (iv) address the in vivo role of endothelial PLC? in causing lung autophagy and evaluate the contribution of this event in the mechanism of lung inflammation and injury. Aim 2 will (i) determine the role of PLC? in suppressing MTOR levels/signaling to cause EC autophagy and inflammation, (ii) determine the in vivo relevance of suppression of endothelial MTOR levels/signaling in causing lung vascular autophagy and inflammatory injury, and (iii) evaluate the therapeutic potential of autophagy inhibition against evolving ALI. These studies will utilize multidisciplinary approaches ranging from biochemical, cellular, and molecular biology to in vivo gene delivery and lung physiology, and take advantage of conditional PLC? and MTOR knockout mice. The creative integration of in vitro and in vivo studies will provide novel insights into the integrated regulation of EC autophagy and inflammation in ALI and may lead to novel therapeutic interventions to control ALI/ARDS.